1. Field of the Invention
The present invention is generally related to a heat exchanger for a marine engine and, more particularly, to a heat exchanger that is integral with an air intake manifold of a V-type engine.
2. Description of the Prior Art
U.S. Pat. No. 5,309,885, which issued to Rawlings et al on May 10, 1994, describes a marine propulsion device including a fuel injected four-cycle internal combustion engine. The internal combustion engine comprises an engine block including a combustion chamber, a fuel vapor separator, a fuel supply mechanism for introducing fuel to the combustion chamber, a conduit communicating between the fuel vapor separator and the fuel supply mechanism for introducing fuel, and a cooling jacket for cooling the fuel vapor separator.
U.S. Pat. No. 3,780,715, which issued to Flitz on Dec. 25, 1973, describes an early fuel evaporation intake manifold. The manifold is provided for an internal combustion engine and includes a low thermal mass, thin metal gasket plate clamped between upper and lower manifold castings and having an integral heat exchanger forming the floor of the riser bore plenum. The gasket plate and cored channel in the lower manifold casting define an exhaust crossover passage having a vertical run incident to the heat exchanger and flaring to a restrictive high aspect-ratio heat transfer duct coextensive with the heat exchanger. The exhaust gases are directly against the heat exchanger at the vertical run and accelerate through the restrictive duct to break up the stagnant fluid film at the heat exchanger or effecting rapid heating thereof to promote greater fuel vaporization during engine warmup.
U.S. Pat. No. 4,258,687, which issued to Mauch et al on Mar. 31, 1981, describes an engine with an integral mounted EGR cooler. An automotive type V-8 engine has an exhaust gas recirculation system wholly contained within its intake manifold, and a flat, sandwich type EGR cooler is constructed in be integrally mounted to the underside of the manifold in the valley of V-8 over the combination valley cover-manifold gasket, without the use of hoses, clamps and other paraphernalia normally associated with externally mounted EGR coolers.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
In marine engine applications, in which a closed cooling system is provided, the coolant within the closed cooling system is typically cooled through the use of lake or sea water. To accomplish this, a heat exchanger is provided. It would be significantly beneficial if a structure could be provided in which the heat exchanger is disposed in a compact configuration.
A cooling system for a marine propulsion system, made in accordance with a preferred embodiment of the present invention, comprises an internal combustion engine having a plurality of cylinders, with the plurality of cylinders being disposed in a V-shaped configuration with at least a first one of the plurality of cylinders being disposed on a first side of the V-shaped configuration and at least a second one of the plurality of cylinders being disposed on a second side of the V-shaped configuration. A cooling passage is formed within the internal combustion engine to conduct a first cooling fluid in thermal communication with a heat producing component of the internal combustion engine. The heat exchanger is connected in fluid communication with the coolant passage and in fluid communication with a source of a second cooling fluid. The heat exchanger is configured to conduct the first and second cooling fluids in thermal communication with each other. The heat exchanger is disposed between the first and second sides of the V-shaped configuration of cylinders.
The heat exchanger comprises a plurality of tubes within which the second cooling fluid is conducted. The first cooling fluid is conducted within a cavity of the heat exchanger external to the outer surfaces of the plurality of tubes. The first cooling fluid is conducted to flow within a closed circuit comprising the heat exchanger and the cooling passage formed within the internal combustion engine.
In certain embodiments of the present invention, a conduit is disposed within the heat exchanger and in thermal communication with the second cooling fluid. The conduit is connected in fluid communication with a lubrication system of the internal combustion engine in order to conduct a liquid lubricant through the conduit in thermal communication with the second cooling fluid. The conduit comprises a helical tubular structure disposed in an end portion of the heat exchanger in one embodiment of the present invention.
The present invention can further comprise an intake manifold disposed at least partially between the first and second sides of the V-shaped configuration of cylinders. A cavity is formed within the intake manifold and shaped to receive the heat exchanger therein. The heat exchanger is disposed within the cavity formed within the intake manifold, whereby an internal surface of the cavity serves as an outer shell of the heat exchanger.
In the preferred embodiment of the present invention, heat is transferred from the first cooling fluid to the second cooling fluid within the heat exchanger. The second cooling fluid is water which is drawn from a body of water, such as a lake or ocean in which the marine propulsion system is operated. The plurality of tubes is disposed along an axis which is generally parallel to a crankshaft of the internal combustion engine in a particularly preferred of the present invention.